Process for treating heavy oil

ABSTRACT

A process for treating heavy oil by contacting the oil with hydrogen in a reactor containing an activated carbon catalyst having a specified range of Alpha value, and average pore diameter, and pore distribution, to reduce the content of nickel and vanadium in the feedstock and to achieve conversion of the carbon residue for producing a lighter oil. Demetallation capacity of the carbon catalyst is enhanced by the addition of a carbon-reactive oxidant, e.g., steam, under conditions sufficient to form additional carbon surface.

RELATED APPLICATIONS

This case is a continuation in part of U.S. application Ser. No.07/728,663, filed Jul. 11, 1991 and U.S. application Ser. No.07/747,829, filed Aug. 21, 1991, both now abandoned, the contents ofeach being incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for converting and upgrading heavyoils to produce a product suitable for transport through a pipeline andfor further processing.

2. Background of the Art

As high quality crude oils are depleted, an inexpensive substitute foruse as petroleum refinery feedstock becomes more desirable. One suchsubstitute is petroleum residue, or heavy oil, such as that producedfrom the straight run distillation of crude oil. Another substitute forhigh quality crude oils are heavier crude oils.

The world's supply of light, sweet crudes has greatly diminished inrecent years. Refiners have been forced to deal with ever heaviercrudes, containing significantly more metals, while still producing afull spectrum of products. Much of the problem of upgrading theseheavier stocks is due to the presence of so much metal, usually nickeland vanadium. The presence of large amounts of metal, usually inassociation with asphaltenes, presents a formidable upgrading challenge.Some of the worst of these materials are "heavy crudes" while almost asbad are somewhat lighter crudes which contain less asphalt, but evenmore metal. Each type of resource will be briefly reviewed.

Heavy Crudes

Extensive reserves of petroleum in the form of so-called "heavy crudes"exist in a number of countries, including Western Canada, Venezuela,Russia, the United States and elsewhere. Many of these reserves arelocated in relatively inaccessible geographic regions. The UnitedNations Institute For Training And Research (UNITAR) has defined heavycrudes as those having an API gravity of less than 20, suggesting a highcontent of polynuclear compounds and a relatively low hydrogen content.The term "heavy oil" whenever used in this specification means an oilhaving an API gravity of less than 20 and includes both heavy crude oiland heavy petroleum fractions such as petroleum residue produced fromthe distillation of crude oil. In addition to a high specific gravity,heavy crudes in general have other properties in common including a highcontent of metals, nitrogen, sulfur and oxygen, and a high ConradsonCarbon Residue (CCR). The heavy crudes generally are not fluid atambient temperatures and do not meet local specification forpipelineability. It has been speculated that such crudes have resultedfrom microbial action which consumed alkanes leaving behind the heavier,more complex structures which are now present.

A typical heavy crude oil is that recovered from tar sands deposits inthe Cold Lake region of Alberta in northwestern Canada. The compositionand boiling range properties of a Cold Lake crude (as given by V. N.Venketesan and W. R. Shu, J. Canad. Petr. Tech., page 66, July-August1986) is shown below.

High Metal Content Crudes

Although considerably lighter than the "heavy crudes", the high metalcontent crudes such as Mayan crude present similar processingdifficulties. The high metals crudes are those which are difficult toprocess by conventional catalytic methods such that at least the highestboiling portions of these crudes are thermally upgraded by coking orvisbreaking. Generally the heaviest fractions, which contain most of themetal, are separated from the lighter fractions by fractionation orvacuum fractionation to recover a gas oil or vacuum gas oil and lighterfractions which with difficulty can be upgraded catalytically.

Unfortunately, the lighter fractions obtained from high metals crudesstill contain relatively large amounts of metals. Although the gas oiland vacuum gas oil fractions can be upgraded in, e.g., an FCC, the metalcontent of such gas oils is so high that some form of metalspassivation, or hydrotreating of the feed to remove metals, is usuallynecessary.

Heavy oils are not extensively used as a refinery feed in part becausetheir viscosity is too high for transmission through a pipeline and inpart because their metals content, especially nickel and vanadium, istoo high. Nickel and vanadium are present as stable nitrogen complexesin the form of porphyrins, which cause severe refinery problems, poisoncatalysts and are detrimental to the quality of finished products.

The progressive depletion and rising cost of high quality crudes hascreated a need for a process for inexpensively converting heavy oils topipelineable syncrudes, preferably in a way that will not makedownstream processing operations more difficult. Such a process wouldaugment the supply of available crude and would make it possible forrefiners to blend syncrude with a more conventional feed for catalyticcracking and hydrocracking.

Heavy oils can be pumped through heated pipelines but this requires theexpenditure of a considerable amount of energy. Hence, heavy oils areusually treated by processes such as visbreaking, coking anddeasphalting. A description of these processes may be found in ModernPetroleum Technology, Fourth Edition, edited by Hobson & Pohl, pp. 281to 288 and 422 to 423.

However, these processes are accompanied by certain drawbacks.Visbreaking, i.e., viscosity breaking, is a relatively mild thermalcracking process which yields reduced viscosity products. However, withmost heavy oils conventional visbreaking yields incompatible two phaseproducts. Coking is a more severe thermal cracking process whichconverts residual oils such as pitch and tar into gas, naphtha, heatingoil, gas oil and coke. Coking requires a large refinery operation.Deasphalting produces low yields of pipelineable oil.

Fractionation to concentrate the lighter portions of the whole crude issomewhat effective but the fractionation itself changes the crudecausing metals to migrate into the lighter fractions. The gas oil orvacuum gas oil fractions obtained by fractionation are believed to bemore contaminated with metal than can be accounted for by assuming thatall, or almost all, of the metals are associated with the asphalticresidual portion of the crude.

Hydrotreatment has been used as a method for upgrading heavy oil andcatalysts employed therein include CoMo/alumina and activated carbon.

U.S. Pat. No. 3,715,303 discloses the use of activated carbon as acatalyst in the hydrotreatment of residual hydrocarbons. A requiredcomponent of the catalyst described therein in an alkali or alkalineearth metal compound such as potassium hydroxide to render the catalystbasic.

U.S. Pat. No. 3,812,028 discloses the use of an activated carboncatalyst for the hydrotreatment of a feed containing polynucleararomatic compounds by passing the feed through a reaction zonemaintained at an elevated temperature and at a hydrogen partial pressurein excess of 2200 psig, and including a catalyst composited of activatedcarbon and a metallic component.

U.S. Pat. No. 4,518,488 discloses a process for hydrotreating feedstockscontaining asphaltenes using a catalyst composited from a porous carbonmatrix with a uniform dispersion of metal thereon.

U.S. Pat. No. 4,988,434 discloses a process for reducing metalcontaminants in a hydrocarbonaceous liquid, e.g., atmospheric bottoms,by contacting the liquid with an activated-carbon supported catalyst.

SUMMARY OF THE INVENTION

A goal of the process of the present invention is to upgrade heavy oilto facilitate its pipeline transportation and further processing. Theupgrading includes reducing the Conradson Carbon Residue value, reducingthe amount of high boiling (e.g. 1000° F.+) fraction of the oil,demetallation and, optionally, desulfurization and asphalteneconversion. More particularly, an object of the present invention is toincrease the catalyst life and efficacy of the activated carbon used fordemetallation.

The foregoing is accomplished by means of the hydrotreating process ofthis invention which comprises hydrotreating a heavy oil feedstock inthe presence of a hydrotreating catalyst composition containingactivated carbon, the carbon having an average pore diameter of fromabout 15 A to about 70 A and a pore diameter distribution which includessubstantially greater pore area and pore volume in the pore diameterrange of from about 100 Å to about 400 A.

The catalyst composition can also comprise a molybdenum or tungstencomponent, and a cobalt or nickel component.

The hydrocarbon oil feedstock is, for example, a 650° F.+ boilingatmospheric distillation residuum. The hydrotreating process typicallyachieves at least about a 23% reduction of the original metal content(i.e. Ni and V content) together with significant reductions in thesulfur content and Conradson Carbon Residue.

The demetallation and upgrading properties of the activated carboncatalysts are deleteriously subject to catalyst aging. When metals suchas nickel and vanadium deposit on carbon catalysts they do not penetratethe core of the catalyst because of diffusion limitations. Thus, theinterior of the demetallation catalyst is ordinarily not used to itstheoretical capacity. Accordingly, it would be desirable to provide aprocess which utilizes the catalyst more closely to its theoreticalcapacity.

The present invention relates to a process for hydrotreating ahydrocarbon oil feedstock in the presence of a carbon-reactive oxidantand a catalyst composition comprising activated carbon possessing a porevolume in the 100 A to 400 A pore diameter range of at least about 0.08cc/g and an average pore diameter of from about 15 A to about 100 A,wherein said oxidant reacts with the activated carbon to form additionalcarbon surface area during said hydrotreating. Such surface area can beincreased by at least 1%, 5%, 10% or even 25% or more. The processresults in increased demetallation capacity of the activated carboncatalyst.

The present invention utilizes the addition of a carbon-reactiveoxidant, such as H₂ O (steam), O₂, and/or CO₂, to the hydrotreatingprocess in order to extend catalyst life by inducing reactions, e.g.,steam-carbon reactions, in the carbon catalyst component in order tobring about the formation of additional surface area of the activatedcarbon during hydrotreating. The demetallation capacity of the carboncomponent is increased as a result of the constantly developing porestructure therein. Metal present in the outer part of the carboncatalyst particle can be oxidized thereby exposing fresh carbon in thecatalyst particle interior. Furthermore, besides developing additionalpore structure, the use of steam with a cobalt/molybdenum ornickel/tungsten carbon catalyst can cause migration of such metals intothe newly developing pores by the formation of sulfide species, e.g.,MoS_(x) and CoS_(y), into mixed oxide-sulfide species.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph illustrating the demetallation capability of differentactivated carbon hydrotreating catalysts.

FIG. 2 is a graph illustrating a comparison of the demetallation ofheavy oil with Petrodarco A™ carbon as hydrotreating catalyst inaccordance with this invention and CoMo/alumina as hydrotreatingcatalyst in accordance with known technology.

FIG. 3 is a graph illustrating BJH desorption pore volume data forvarious activated carbon hydrotreating catalysts.

FIG. 4 is a graph comparing the cumulative adsorption pore volume ofDarco® carbon with that of Alfa™ carbon and alumina.

FIG. 5 is a graph illustrating data for the conversion of heavy oil byseveral selected activated carbon catalysts.

FIG. 6 is a graph illustrating the demetallation of a heavy oil overactivated carbon catalyst.

FIG. 7 is a depiction of extrapolated data indicating that steam willreact with carbon at hydrotreating conditions.

FIG. 8 is a graph of carbon catalyst surface area (m² /g) versus wt %loss from air oxidation of shot coke. The figure shows that air oxidizedshot coke with less than 5 m² /g of surface area can increase itssurface area by a factor of 5 with a 10% weight loss in carbon.

FIG. 9 is a graph comparing pore volume (cc/g×10⁻⁶) with average porediameter of air oxidized shot coke with 23 m² /g surface area vs. 6-8mesh activated carbon with 987 m² /g. The figure shows that a shot cokesample with no measurable pore volume has developed a pore structurefrom air oxidation with some pores having a pore diameter above 100 A.

FIG. 10 is a graph of carbon catalyst surface area (m² /g) versus wt %loss from oxidation for a shot coke subjected to carbon dioxideoxidation which shows surface areas similar to those from air oxidation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with a preferred embodiment of the present invention, aheavy hydrocarbon oil is upgraded by a hydrotreating process using anactivated carbon catalyst. As indicated above, by "heavy oil" or "heavyhydrocarbon oil" is meant a hydrocarbon oil with an API gravity of lessthan about 20. The hydrocarbon oil undergoes visbreaking, demetallation,and reduction of carbon residue (as measured by Conradson CarbonResidue, "CCR"). Some desulfurization and asphaltene conversion alsooccurs. The upgraded product can then be used as feed to a fluidcatalytic cracker.

Feedstock

The heavy hydrocarbon oil feedstock used in the present invention canbe, for example, heavy crude oil, vacuum or atmospheric distillationresiduum or various other fossil fuels such as tars and oil or shaleoil. Light oils can also be treated with the catalyst composition of thepresent invention to reduce the content of unwanted metals such asnickel and vanadium.

The soluble components include all of the light components of the crudeand the heavier components which are readily soluble in aliphaticsolvents. Asphaltenes are generally insoluble in aliphatic solvents. Theasphaltene fraction from a whole heavy crude can contain almost all ofthe metals depending upon solvent used for deasphalting. The maltenefraction will have a greatly reduced metals content compared to theasphaltene fraction. The maltenes are somewhat soluble in aliphaticsolvents, depending on deasphalting conditions.

The heavy oils contemplated for use herein have very little lightcomponents boiling below 650° F. and an abundance of 650° F. + materialand asphaltenes. In general terms, the whole crudes contemplated for useherein will have a 50 wt. % boiling point at atmospheric pressure inexcess of about 650° F. Frequently, the 40% and even the 30 volume %boiling points of such crudes will exceed 1000° F. such that the crudeswill be considered non-distillable. Most heavy crudes are asphaltenic innature but a few are not. Asphaltenic crudes contain a high proportionof naphthenic and aromatic components and a low paraffin content and arecharacterized by a low API gravity, e.g., of less than about 30 for thewhole crude and less than about 20 API gravity for the 650° F. +fraction. Whole crudes have a CCR content usually in excess of about 10wt % and a pentane insoluble asphaltene content of at least about 10 wt% (using 10:1 pentane:oil). Many of the heavy crudes have a specificgravity above about 0.9. The 650° F. + fraction of some heavy crudes isso heavy that the specific gravity is about 1.0 (an API gravity of lessthan about 10) and will sink, not float, in water. More than 25% of thecrude boils above 1000° F.

The heavy oils generally contain large amounts of metals such as nickeland vanadium, much, and usually most of which, are coordinated byporphyrin or "porphyrin like" structures. These porphyrins or "porphyrinlike" structures coordinate Ni and V in complex aromatic structures thatare asphaltic in nature. Typically, heavy oils contain more than 5 ppmby weight of Ni and more than 25 ppm by weight of V on a whole crudebasis. The porphyrins undergo degradation reactions which disrupt thearomaticity of the porphyrin rings and transform metal-coordinatedporphyrin or metalloporphyrins into metal-coordinated polypyrrolicspecies. More details on such heavy crudes and porphyrin degradationreactions are provided in "Degradation of Metalloporphyrins in HeavyOils Before and During Processing" L. A. Rankel, Fossil FuelsGeochemistry, Characterization and Processing, ACS Symposium Series No.344, Chapter 16, (ACS) 1987 ed. R. H. Filby and J. F. Branthayer, whichis incorporated herein by reference.

Typical feedstocks, a heavy oil (a Cold Lake crude, Lower Grand Rapids)and a topped Mexican heavy crude (Mayan 650° F. + Primary Production)are shown below. The similarities are evident.

    ______________________________________                                        PROPERTIES OF 650° F. FRACTIONS                                                      Mayan Cold Lake                                                 ______________________________________                                        % C             84.0    83.8                                                  H               10.4    10.3                                                  N                0.06    0.44                                                 O                0.97    0.81                                                 S                4.7     4.65                                                 CCR             17.3    12.3                                                  % C7-Insoluble  18.5    15.0                                                  Ni, ppm         78      74                                                    V, ppm          372     175                                                   Boiling Range:                                                                75-400° F.                                                                              0.62    1.3                                                  400-800° F.                                                                            21.7    --                                                    400-650° F.                                                                            --      15.2                                                  800-1050° F.                                                                           19.0    --                                                    650-1000° F.                                                                           --      29.7                                                  1050° F.+                                                                               58.71  --                                                    1000° F.+                                                                              --      53.8                                                  ______________________________________                                    

Typical levels of (Ni+V) in the heavy oils contemplated for use hereinwill exceed 50 wt ppm (total Ni+V), and frequently will exceed 100 oreven 150 wt ppm (Ni+V) based on the whole crude. There is no physicalupper limit on metals concentrations contemplated for use herein.

The heavy oils usually contain relatively large amounts of sulfur whichis advantageously reduced by the method of the present invention.

Carbon-Reactive Reductant

The present invention utilizes at least one suitable carbon-reactivereductant which reacts with the activated carbon catalyst in such a wayas to increase its surface area. Various reductants can be employed toeffect such surface area enhancement, such as H₂ O (or steam), carbondioxide (CO₂), or oxygen-containing gas, e.g., air. Carbon can bereacted with these reductants as shown below:

(1) C+2H₂ O→2H₂ +CO₂

(2) 2C+2H₂ O→CH₄ +CO₂

(3) C+CO₂ →2CO

(4) C+O₂ →CO₂.

Reaction Conditions

The reactor can be of the fixed bed type or a fluidized or moving bedreactor. A trickle bed type reactor is preferred.

Processing may be carried out at a temperature of from about 500° F. toabout 1200° F., a pressure of from about 0 psig to about 4000 psig, anda weight hourly space velocity (WHSV) of from about 0.1 to about 10hr-1.

Processing conditions preferably include a temperature range of fromabout 600° to about 1000° F., a pressure of from 500 to about 2500 psig,and a WHSV of from about 0.2 to about 5 hr-1.

Hydrogen circulation can range from about zero to about 40,000 SCFH2/bbl of feed depending on hydrogenation activity. Typically, the rangeof hydrogen circulation of the present method is from about 300 SCF/bblto about 6000 SCF/bbl.

Steam can be added to heated feed upstream of the reactor or water canbe added to the feed and the steam generated in the reactor. Water orsteam can be added continually or intermittently as needed to improvethe activity of the carbon catalyst. Typically, steam is added toprovide a steam partial pressure of 1 to 3000 psig, preferably 10 to1000 psig, e.g., 20 to 800 psig. Alternatively, water or steam can beadded directly to the reactor. Carbon dioxide can be added in likemanner. In one embodiment, feed and hydrogen can be discontinued for ashort time, the reactor flushed with N₂ or CO₂ and then carbon dioxide,steam or oxygen is fed to the reactor in order to develop new porestructure for the catalyst. Hydrogen cannot be present in the reactorwhen air or O₂ is being used.

The addition of steam results in the steam-carbon reaction taking placein or on the carbon component of the catalyst. P. L. Walker, "Advancesin Coal Utilization Technology", Institute of Gas Tech , May 14-18,1979, Louisville, Ky., Chapter 13, provides data showing the effect ofpressure and temperature on steam reactions with Illinois No. 6 coal.Extrapolation of these data (see FIG. 7) indicates that at temperaturesbelow 500° C., at least 50 atmospheres of pressure are required.Accordingly, it is shown that, for present purposes, pressures of 50 to3000 psig, preferably 500 to 2500 psig, e.g., 700 to 2000 psig arerequired for hydrotreating and in this regime, water or steam additionwill cause reaction with carbon (see Table A).

Steam-carbon reaction promoters can greatly facilitate the steam-carbonreaction. The addition of KOH to graphite causes atmospheric pressuresteam reactions at 400° to 600° C., according to F. Delannay, et al.,Appl. Catalysis, 10, 111 (1984). Pereira, et al., J. Cat., 123, 463(1990) teach that K--Ca--O_(x) catalysts can be added to effect lowtemperature steam-carbon reactions. Klaus J. Huttinger, et al., Fuel,Vol. 64, p. 491 (1985) describe the melting and wetting behavior ofvarious alkali compounds in catalytic water vapor gasification ofcarbon. Accordingly, it is within the scope of the present invention toemploy steam-carbon reaction promoters as necessary to promotesteam-carbon reactions under the hydrotreating process conditions usedherein. Typically, such promoters can be added by weight percent rangingfrom 0.001 to 5%, preferably 0.1 to 2% of promoter in the catalyst.

It may not be necessary to add promoters to the carbon catalysts tofacilitate the steam-carbon reaction. These activated carbons canalready contain K, Fe, Ca, Ni, Li, and V (see Table B, below for all themetals), which are metals known to promote the steam-carbon reaction(see Ed. Peter A. Thrower, Chemistry and Physics of Carbon, Vol. 21,Marcel Dekker, 1989). If promoters are to be added, compounds or saltswith the following metals can be used: K, Ca, Ni, V, Ba, Mg, Mn, Zn, andP.

                  TABLE A                                                         ______________________________________                                        Carbon Catalyst Properties Comparison                                                           Alfa   Shot    Darco                                                          Carbon Coke    Carbon                                       ______________________________________                                        Surface Area, m.sup.2 /gm (M-374)                                                                 946      <5      712                                      Real Density, gm/cc (M-1502)                                                                      2.072    1.352   1.990                                    Particle Density, gm/cc (M-1503)                                                                  1.023    1.286   .676                                     Pore Volume (M-1504)                                                                              .495     .038    .977                                     Average Pore Diameter, A (M-1505)                                                                 20       --*     54                                       Alpha Value         .sup.˜ 4.8 .sup.˜ 3.0                         C, %                90.4     88.2    81.1                                     H, %                <0.5     2.6     1.1                                      N, %                0.9      3.76    7.6                                      S, %                0.9      1.89    0.5                                      Ash, %              3.4      1.33    10.0                                     Fe, %               0.3      0.12    0.3                                      Al.sub.2 O.sub.3, % 1.1              3.5                                      SiO.sub.2, %        1.3              10.0                                     Cu, ppm             0.47             40                                       K, %                0.24             .0025                                    V, ppm              54               --                                       Ca, %               0.37             0.2                                      Li, ppm             <50              <48                                      Mg, %               .013             .096                                     Ni, %                        .08                                              ______________________________________                                         *could not be measured                                                   

As noted above, CO₂ can also be used to effect oxidation of the carboncatalyst. Treatment with CO₂ can be carried out at temperatures of 300°to 800° C., preferably 400° to 600° C. at CO₂ partial pressures rangingfrom 1 to 1000 psig, preferably 50 to 500 psig. Preferably, the catalystis treated so that no greater than 20 percent of its weight is lost overthe lifetime of the catalyst, in order to avoid surface area losses orcollapse of the catalyst particle.

Air or O₂ can also be used to effect oxidation of the carbon catalyst.Treatment with O₂ can be carried out at temperatures of 300° to 800° C.,preferably 400° to 700° C. at O₂ partial pressures ranging from 1 to 300psig, preferably 10 to 500 psig. Preferably, the O₂ is provided in theform of air. However, if air or oxygen is used, the hydrogen flow to thereactor must first be stopped and the reactor flushed out with N₂ or CO₂to remove the hydrogen before air flow is begun.

The feed is initially heated to render it fluid so that it can be pipedinto the reactor.

Hydrotreating Catalyst

The activated carbon hydrotreating catalyst of the present inventionpossesses a pore volume in the 100 Å to 400 Å pore diameter range of atleast about 0.08 cc/g and preferably at least about 0.2 cc/g and anaverage pore diameter of from about 15 Å to about 100 Å and preferablyfrom about 40 Å to about 90 Å. Advantageously, the activated carbonpossesses the additional properties set forth in Table 1. This activatedcarbon is neat, i.e., contains no additional material.

                  TABLE 1                                                         ______________________________________                                                        Broad Range                                                                              Preferred                                          ______________________________________                                        Crush Strength, lbs                                                                             ≧8.0  ≧11.0                                   Surface area, m.sup.2 /g                                                                        100          200-800                                        Real density, g/cc                                                                              1.9-2.2      1.9-2.2                                        Particle density, g/cc                                                                          0.6-1.0      0.6-1.0                                        Mesh Size         2-100        4-20                                           Alpha Value       2.9-7        3.0-6                                          Pore area in the 100 A to                                                                       ≧18   ≧50                                     400 A pore diameter range                                                     ______________________________________                                    

Average pore diameter and other above properties are determined by thefollowing methods.

Real density was determined by gas pychnometry using a MicromeriticsAutopychnometer 1320.

The particle density of a catalyst or similar porous material can bedetermined by measuring the amount of mercury necessary to fill acontainer of known volume after a sample of known weight has beenintroduced. Mercury does not "wet" most porous solids and, as a result,will not enter its pores. In this method, mercury is allowed to flowinto the sample tube under atmospheric pressure (14.7 psia). At thispressure only pores with a diameter, d, greater than about 150,000 A, or15 microns, will be filled. This estimate of minimum pore diameter isbased on the following equation:

    d=(4 γ cos Θ)+P

where γ is the surface tension of mercury, Θ is the wetting or contactangle of mercury, and P is the pressure applied to mercury for porepenetration. This equation reduced to:

    d215.1+P=215.1+14.7≃15 microns

wherein d and P are expressed in units of microns and psia,respectively.

The pore volume is determined as follows: ##EQU1## wherein D_(p)=particulate density, g/cc

D_(r) =real density, g/cc

Calculation of the average pore diameter is determined as follows:##EQU2## where PV=pore volume, cc/g SA=surface area, m² /g

The surface area, expressed as m² /g, was determined by the amount of amonomolecular layer of N₂ adsorbed onto a sample between ice and liquidN₂ temperature. A Micromeritics 2200 Surface Area Analyzer was used forthis measurement.

A Micromeritics Digisorb 2600 instrument was used to determine porediameter distribution. The adsorption and desorption isotherms fornitrogen at different pressures were plotted and pore size and pore areadistribution was calculated.

When Alpha value is examined, it is noted that Alpha value is anapproximate measure of the catalytic cracking activity of a catalystcompared with a standard catalyst and it gives the relative rateconstant (rate of normal hexane conversion per volume of catalyst perunit time). It is based on the activity of the highly activesilica-alumina cracking catalyst taken as an Alpha of 1 (RateConstant=0.016 sec-1). The Alpha value test is described in U.S. Pat.No. 3,354,078 in the Journal of Catalysis, Vol. 4, p. 527 (1965); Vol.6, pg. 278 (1966); and Vol. 61, p. 395 (1980), each incorporated byreference as to that description. The experimental conditions of thetest used herein include a constant temperature of 538° C. and avariable flow rate as described in detail in the Journal of Catalysis,Vol. 61, p, 395. Alpha values were measured in atmospheres of helium andhydrogen.

Alpha values give an indication of the acid cracking sites of acatalyst, i.e., the higher the Alpha value the higher the acid crackingactivity. The activated carbon used in the present invention mayoptionally contain, or be associated with, one or more components toimprove cracking activity, such as silica and/or alumina.

The activated carbon of the present invention is preferably preparedfrom lignite. Coals, such as anthracite, bituminous coal, and ligniteare classified according to moist, mineral-matter-free energy content inaccordance with the measuring requirements set by ASTM Standard D 388.In this method of classification, lignite has a moist energy of lessthan 8300 BTU/lb. A lignite based activated carbon suitable for use inthe method of the present invention is Darco® brand carbon availablefrom American Norit Company, Inc., of Jacksonville, Fla. Another lignitebased activated carbon suitable for use in the method of the presentinvention is designated as Pettedarco A™ and is also available fromAmerican Norit Company Inc.

Other types of lignite based activated carbons are commerciallyavailable but are outside the scope of this invention. Thus, forexample, Alfa™ (Alfa Products, Danvets, Mass.), an activated carbonwhich does not possess the requisite pore distribution properties of theactivated carbon catalyst employed in the process of the presentinvention, is inferior to the catalysts herein.

Non-lignite based activated carbons may also be used in the method ofthe present invention provided they possess suitable pore properties.For example, a peat based activated carbon designated as Norit Rox™ 0.8is available from American Norit Company and is suitable for use in thehydrotreating process of the present invention.

One surprising result is the effectiveness of a relatively small averagepore diameter. Compared with cobalt-molybdenum on alumina (CoMo/Al203),which has an average pore diameter of over 70A, Darco® carbon has anaverage pore size of about 54A.

The pore volume distribution is an important factor to consider withrespect to activated carbons. It has been found that the pore volumedistribution in the 79A to 500A pore diameter range is particularlyimportant with respect to treating processes for heavy oil to facilitatethe catalytic reaction or large oil molecules. Heavy oils containmolecules with diameters greater than 50A, a significant percentage ofwhich have diameters in the 200A to 400A range. Large pores in thecatalyst can accommodate the molecules of this size range therebyfacilitating demetallation, desulfurization, catalytic cracking andhydrogenation at the pore sites.

Table 2 sets forth the pore distribution comparison of Darco® carbon,Alfa™ carbon, alumina, Petrodarco A™ carbon and Norit Rox™ 0.8 carbon.Both the incremental pore volumes and incremental pore areas arecompared. As can be seen, Darco® carbon has significant catalyst surfacearea in the 100A to 400A range.

                                      TABLE 2                                     __________________________________________________________________________    CoMo ON ACTIVATED CARBON                                                      Desorption Pore Distribution                                                  Pore Diameter                                                                         Average                                                                            Incremental                                                                          Cumulative                                                                          Incremental                                                                          Cumulative                                   Range   Diameter                                                                           Pore Vol.                                                                            Pore Vol.                                                                           Pore Area                                                                            Pore Area                                    (Å) (Å)                                                                            (cc/g) (cc/g)                                                                              (sq. m/g)                                                                            (sq. m/g)                                    __________________________________________________________________________    Co/Mo Darco ® Carbon                                                      600-400 500  0.011864                                                                             0.011864                                                                            0.996  0.996                                        400-200 300  0.054064                                                                             0.065928                                                                            8.584  9.580                                        200-150 175  0.045044                                                                             0.110972                                                                            10.631 20.210                                       150-100 125  0.067192                                                                             0.178163                                                                            22.608 42.818                                       100-50   75  0.124167                                                                             0.302330                                                                            72.910 115.728                                      50-30    40  0.144508                                                                             0.446839                                                                            148.471                                                                              264.199                                      30-15     22.5                                                                             0.056684                                                                             0.503528                                                                            111.886                                                                              376.084                                      Co/Mo Alfa ™ Carbon                                                        600-400 500  0.001542                                                                             0.001542                                                                            0.141  0.141                                        400-200 300  0.002465                                                                             0.004007                                                                            0.373  0.513                                        200-150 175  0.001198                                                                             0.005205                                                                            0.277  0.790                                        150-100 125  0.001708                                                                             0.006913                                                                            0.585  1.376                                        100-50   75  0.005562                                                                             0.012475                                                                            3.097  4.473                                        50-30    40  0.019280                                                                             0.031855                                                                            21.073 25.546                                       30-15     22.5                                                                             0.157588                                                                             0.189443                                                                            353.340                                                                              388.886                                      __________________________________________________________________________

Table 3 sets forth the pore volumes and pore areas in the 100A to 400Apore diameter range. For example, comparing pore area in the 100A to400A pore diameter range (see Table 3), Darco® carbon has a pore area of52.103 m² /g whereas Alfa™ carbon has 1.226 m² /g in the same range andalumina has a pore area of 6.165 m² /g in the same pore diameter range.With respect to pore volume, Darco® carbon has a pore volume of 0.205864cc/g in the 100A to 400A pore diameter range, whereas Alfa™ carbon has a0.005136 cc/g in that range, and alumina has a pore volume of 0.02422cc/g in the 100A to 400A pore diameter range.

                  TABLE 3                                                         ______________________________________                                        Pore Volumes and Pore Areas                                                   in the 100 A to 400 A Pore Diameter Range                                                  Pore Volume                                                                            Pore Area                                                            (cc/g)   m.sub.2 /g                                              ______________________________________                                        Darco ®    0.205864   52.103                                              Petrodarco ™ A                                                                            0.204596   49.118                                              Norit Rox ™ 0.8                                                                           0.085919   18.649                                              Alfa ™      0.005136    1.226                                              Alumina        0.02422     6.165                                              ______________________________________                                    

The following examples illustrate a comparison of the hydrotreatingcatalyst of the present invention as exemplified by Darco®, PetrodarcoA™, and Norit Rox™ 0.8 in comparison with CoMo/Al03, Alfa™ activatedcarbon, and shot coke (a non-activated carbon) with respect to thedemetallation of 650° F.+ residue feedstock. CoMo/Al₂ O₃ is a commonlyused catalyst for hydroprocessing. The results show that neat activatedcarbons compare favorably with CoMo/Al₂ O₃ in term of the effectivenessof converting high boiling fractions of the feedstock and in terms ofdemetallation and reduction of Conradson Carbon Residue. Use ofactivated carbon is advantageous because it is less expensive thanCoMo/Al₂ O₃ and the removed metals can be easily recovered by combustingthe catalyst after use to obtain a metals rich ash that can be acidextracted for metals recovery or disposed of with reduced weight andvolume as compared to an alumina based catalyst. Since catalysts areusually disposed of in landfills, the environmental impact as well asthe disposal costs can be reduced by about 50% to 75%.

EXAMPLE 1

A 650° F.+ atmospheric distillation residue fraction was provided foruse as feedstock in the following examples. The feedstock has theproperties set forth in Table 4, below.

                  TABLE 4                                                         ______________________________________                                        650° F.+ Resid                                                         ______________________________________                                        Carbon, %              84.07                                                  Hydrogen, %            10.65                                                  Nitrogen, %             0.30                                                  Oxygen, %               0.81                                                  Sulfur, %               4.23                                                  CCR, %                 12.03                                                  Asphaltenes (Pentane insolubles), %                                                                  15.97                                                  Nickel, ppm            32                                                     Vanadium, ppm          104                                                    B.P. Range °F.  Fraction                                               420-650                  2.50%                                                650-850                 29.25%                                                850-1000                19.54%                                                1000+                   48.71%                                                ______________________________________                                    

The feedstock of Table 4 was hydrotreated in a trickle bed micro unitreactor of standard design at 1500 psig H₂ partial pressure, 5800 SCF H₂/bbl. circulation, and 0.5 hr⁻¹ WHSV.

The trickle bed reactor was charged with 11.23 grams of catalyst and 30cc of sand. The feed delivery was 5.8 cc/hr. Standard presulfiding ofthe catalyst was employed with 2% H₂ S in hydrogen. The run time andtemperature protocol was as follows:

1) 750° F. for 7 days

2) 775° F. for 7 days

3) 750° F. for 2 days

The micro unit reactor incorporated a bottoms receiver held at 200° C.to drive off volatiles, a 2° C. liquid cooled trap condensed low boilingcomponent. Gas samples were analyzed with a gas sampling system withbombs. Off gas volumes were measured with a wet test meter.

A CoMo/Al₂ ₃ catalyst was provided, the catalyst having the propertiesshown in Table 5 below.

The catalyst was prepared with conventional methodology with themolybdenum incorporated first to prevent the cobalt from formingcobalt-alumina spinel structures.

The feedstock was hydroprocessed with the CoMo/Al₂ O₃ catalyst and thedemetallation results are set forth in Table 6 below.

                  TABLE 5                                                         ______________________________________                                        CoMo/Al.sub.2 O.sub.3 Catalyst Properties                                     ______________________________________                                        Co %                2.4                                                       Mo %                8.4                                                       Surface Area, m.sup.2 /g                                                                          about 256                                                 Real Density, g/cc   3.419                                                    Particle Density, g/cc                                                                            --                                                        Pore Volume, cc/g    0.515                                                    Average Pore Diameter, A                                                                          71                                                        Alpha Value         9.8                                                       ______________________________________                                    

EXAMPLE 2

A neat Alfa™ carbon catalyst was provided. The catalyst has theproperties shown in Table 7.

The feedstock of Table 4 was hydroprocessed in a trickle bed reactorunder the same conditions as those of Example 1 with the exception that11.28 grams of Alfa™ activated carbon (without cobalt or molybdenum) wasused as the catalyst. The results of the hydroprocessing are set forthbelow in Table 8.

                                      TABLE 6                                     __________________________________________________________________________    Hydroprocessing Results for CoMo/Al.sub.2 O.sub.3                             Sample                                           % Asphaltene                 No. °F.                                                                       t (days)                                                                           % Conversion.sup.1                                                                    % deM.sup.2                                                                        % deS.sup.3                                                                       % deNi.sup.4                                                                       deV.sup.5                                                                        deCCR.sup.6                                                                        % Asphaltene                                                                         Conversion.sup.7             __________________________________________________________________________    1)  750                                                                              1.7  42.50   67.9 83.5                                                                              58.4 70.8                                                                             52.0 --     --                           2)  750                                                                              6.9  35.03   62.9 80.8                                                                              49.5 67.1                                                                             47.2 --     --                           3)  775                                                                              8.7  55.55   76.3 84.6                                                                              68.3 78.8                                                                             56.9  7.60  52.4                         4)  775                                                                              15.3 49.77   70.6 80.6                                                                              56.4 74.9                                                                             49.5 --     --                           5)  750                                                                              16.7 35.66   55.7 71.9                                                                              37.2 61.4                                                                             42.4 10.94  31.5                         __________________________________________________________________________     .sup.1 Percent reduction of 1000° F.+ fraction in feed                 .sup.2 Percent Total Demetallation (Ni + V removal)                           .sup.3 Percent Desulfurization                                                .sup.4 Percent Nickel removal                                                 .sup.5 Percent Vanadium removal                                               .sup.6 Percent Conradson Carbon Residue reduction                             .sup.7 Deasphalted resid using 10 cc pentane: 1 g resid                  

                  TABLE 7                                                         ______________________________________                                        CATALYST PROPERTIES                                                           (6-8 Mesh Alfa ™ Carbon)                                                   ______________________________________                                        Surface Area, m.sup.2 /g                                                                         946                                                        Real Density, g/cc 2.072                                                      Particle Density, g/cc                                                                           1.023                                                      Pore Volume, cc/g  0.495                                                      Average Pore diameter, A                                                                         20                                                         Alpha Value        3.6                                                        C, %               90.42                                                      H, %               <0.5                                                       N, %               0.93                                                       S, %               0.87                                                       Ash, %             3.39                                                       Fe, %              0.33                                                       Al.sub.2 O.sub.3, %                                                                              1.05                                                       SiO.sub.2, %       1.29                                                       Cu (ppm)           0.047                                                      K, %               0.024                                                      Ni (ppm)           29                                                         V (ppm)            49                                                         Cr (ppm)           66                                                         Cl (ppm)           <13                                                        Na (ppm)           612                                                        Ca, %              0.037                                                      Li, (ppm)          <50                                                        Mg, %              0.013                                                      ______________________________________                                    

EXAMPLE 3

A neat Darco® carbon catalyst was provided. The catalyst has theproperties shown in Table 9.

The feedstock of Table 4 was hydroprocessed in a trickle bed reactorunder the same conditions as those of Example 1 with the exception that11.28 grams of Darco® 12-20 mesh

                                      TABLE 8                                     __________________________________________________________________________    Hydroprocessing Results for Alfa ™ Carbon (6-8 Mesh)                       Sample                                        % Asphaltene                    No. °F.                                                                       t (days)                                                                           % Conversion                                                                          % deM                                                                             % deS                                                                             % deNi                                                                             deV                                                                              deCCR                                                                             Asphaltene                                                                          Conversion                      __________________________________________________________________________    1)  750                                                                              1.9  17.80   30.2                                                                              19.1                                                                              22.1 32.7                                                                             20.2                                                                              --    --                              2)  750                                                                              6.9  17.29   32.8                                                                              13.9                                                                              33.8 32.4                                                                             17.1                                                                              --    --                              3)  775                                                                              8.9  30.15   48.0                                                                              25.8                                                                              38.9 50.8                                                                             29.8                                                                              13.04 18.3                            4)  775                                                                              12.7 24.12   41.2                                                                              19.1                                                                              31.6 44.2                                                                             20.7                                                                              --    --                              5)  750                                                                              13.8 15.78   35.4                                                                              16.8                                                                              30.6 36.8                                                                             13.5                                                                              --    --                              __________________________________________________________________________     activated carbon (without cobalt or molybdenum) was used as the catalyst.     The results of the hydroprocessing are set forth below in Table 10.

                  TABLE 9                                                         ______________________________________                                        CATALYST PROPERTIES                                                           (12-20 Mesh Darco ® Carbon)                                               ______________________________________                                        Surface Area, m.sup.2 /g                                                                         712                                                        Real Density, g/cc  1.990                                                     Particle Density, g/cc                                                                            0.676                                                     Pore Volume, cc/g   0.977                                                     Average Pore diameter, A                                                                         54                                                         Alpha Value        2.9                                                        C, %               81.08                                                      H, %               1.08                                                       N, %               7.60                                                       S, %               0.48                                                       Ash, %             10.04                                                      Fe, %              0.25                                                       Al.sub.2 O.sub.3, %                                                                              3.45                                                       SiO.sub.2, %       9.99                                                       Cu (ppm)           40                                                         K, %                0.0053                                                    Ni (ppm)           16                                                         V (ppm)            37                                                         Cr (ppm)           15                                                         Cl (ppm)           1747                                                       Na (ppm)           1103                                                       Ca, %              0.22                                                       Li, (ppm)          <48                                                        Mg, %               0.096                                                     ______________________________________                                    

EXAMPLE 4

A catalyst was prepared of shot coke which was 30% oxidized in air toincrease its surface area to 44 m² /g.

                                      TABLE 10                                    __________________________________________________________________________    Hydroprocessing Results for Darco ® Carbon (12-20 Mesh)                   Sample                                         % Asphaltene                   No. °F.                                                                       t (days)                                                                           % Conversion                                                                          % deM                                                                             % deS                                                                             % deNi                                                                             deV                                                                              deCCR                                                                             % Asphaltene                                                                         Conversion                     __________________________________________________________________________    1)  750                                                                              1.6  18.86   24.7                                                                              10.4                                                                              25.3 24.6                                                                             13.5                                                                              --     --                             2)  750                                                                              6.8  20.94   23.0                                                                              11.8                                                                              14.6 45.6                                                                             --  --     --                             3)  775                                                                              8.8  34.25   57.4                                                                              21.7                                                                              48.1 71.2                                                                             22.5                                                                              --     --                             4)  775                                                                              14.8 35.01   59.6                                                                              19.6                                                                              40.5 67.8                                                                             21.9                                                                              11.85  25.8                           5)  750                                                                              16.9 17.19   40.4                                                                               9.5                                                                              27.6 47.1                                                                             16.0                                                                              --     --                             __________________________________________________________________________

The properties of the catalyst are set forth in Table 11 below.

The feedstock of Table 4 was hydroprocessed in a trickle bed reactorunder the same conditions as those of Example 1 with the exception that11.23 g of the above mentioned shot coke was employed as catalyst. Theresults of the hydroprocessing are set forth in Table 12.

                  TABLE 11                                                        ______________________________________                                        CATALYST PROPERTIES                                                           (30% Oxidized Shot Coke)                                                      ______________________________________                                        Surface Area m.sup.2 /g                                                                         44                                                          Real Density, g/cc                                                                              --                                                          Particle Density, g/cc                                                                          --                                                          Pore Volume, cc/g --                                                          Average Pore diameter, A                                                                        approximately 16                                            Alpha Value       77.83                                                       C, %              2.98                                                        H, %              3.60                                                        N, %              2.70                                                        S, %              1.51                                                        Ash, %            0.94                                                        Fe, %             --                                                          Al.sub.2 O.sub.3, %                                                                             --                                                          SiO.sub.2, %      --                                                          Cu (ppm)          --                                                          K (ppm)           --                                                          Ni (ppm)           0.098                                                      V (ppm)           0.15                                                        ______________________________________                                    

                  TABLE 12                                                        ______________________________________                                        Hydroprocessing Results for Shot Coke (30% oxidized)                          Sample                                                                        No.   °F.                                                                           t(days) Conversion                                                                            % deM % deS % deCCR                              ______________________________________                                        1)    750    2.2     12.83   0.4   5.0   --                                   2)    750    6.8     13.88   --    7.1   4.4                                  3)    775    8.7     21.29   7.8   9.0   4.1                                  4)    775    14.7    18.01   7.3   8.3   8.4                                  5)    750    16.9    14.06   --    3.5   7.0                                  ______________________________________                                    

EXAMPLE 5

An alkaline version of Darco® carbon, Petrodarco A™ was provided. Thecatalyst has the properties in Table 13.

The feedstock of Table 4 was hydroprocessed in the trickle bed reactorunder the same conditions as those of Example 1 with the exception that11.28 grams of Petrodarco A™ (12-20 mesh) activated carbon was used asthe catalyst.

The results of the hydroprocessing are set forth below in Table 14.

                  TABLE 13                                                        ______________________________________                                        CATALYST PROPERTIES                                                           Petrodarco A ™ (Alkaline Version of Darco ® C)                         ______________________________________                                        Surface Area, m.sup.2 /g                                                                         539                                                        Real Density, g/cc  2.108                                                     Particle Density, g/cc                                                                            0.741                                                     Pore Volume, cc/g   0.875                                                     Average Pore diameter, A                                                                         64                                                         Alpha Value        6.0                                                        C, %               77.25                                                      H, %               0.53                                                       N, %               <0.5                                                       S, %               1.11                                                       Ash, %             28.83                                                      Fe, %              1.80                                                       Al.sub.2 O.sub.3, %                                                                              4.24                                                       SiO.sub.2, %       8.92                                                       Cu(ppm)            69                                                         K, %                0.012                                                     Ni (ppm)           74                                                         V (ppm)            <12                                                        Na, %              0.26                                                       Ca, %              4.39                                                       Li, (ppm)          <49                                                        Mg, %              0.84                                                       ______________________________________                                    

                                      TABLE 14                                    __________________________________________________________________________    Hydroprocessing Results for Petrodarco A ™ (12-20 mesh)                    Sample                                                                        No. °F.                                                                       t(days)                                                                           Conversion                                                                          % deM                                                                             % deS                                                                             % deNi                                                                             % deV                                                                             % deCCR                                     __________________________________________________________________________    1   750                                                                              1.8 23.80 66.0                                                                              22.2                                                                              51.8 70.4                                                                              23.1                                        2   750                                                                              6.9 23.05 58.1                                                                              24.1                                                                              36.7 64.7                                                                              23.0                                        3   775                                                                              8.7 38.52 76.6                                                                              31.9                                                                              53.2 83.8                                                                              33.5                                        4   775                                                                              14.8                                                                              33.66 75.0                                                                              28.1                                                                              52.8 81.8                                                                              32.7                                        5   750                                                                              16.7                                                                              23.36 53.7                                                                              17.5                                                                              30.3 60.9                                                                              19.9                                        __________________________________________________________________________

EXAMPLE 6

An extruded peat based activated carbon, Norit Rox™ 0.8, was employed.The catalyst has the properties shown in Table 15.

The feedstock of Table 4 was hydroprocessed in a trickle bed reactorunder the same conditions as those of Example 1 with the exception that11.28 grams of Norit Rox™ 0.8 12-20 mesh activated carbon (withoutcobalt or molybdenum) was used as the catalyst. The results of thehydroprocessing are set forth below in Table 16.

When activated carbons are compared for demetallation activity forprocessing the feedstock of Table 4, it is found that Petrodarco A™ hasthe highest activity (FIG. 1). The second best is Darco® carbon followedby Norit Rox™ 0.8. The lowest activity is found for Alfa™ carbon (FIG.1). The demetallation activity of Petrodarco A™ carbon is comparable toCoMo/alumina (FIG. 2).

Comparing the BJH desorption pore volume date (FIG. 3) for the fouractivated carbons studied here indicates that the more activedemetallation catalysts, Darco® carbon and Petrodarco A™, have thehighest pore volume distributions in the 200-400A range. Large porevolume in the 200-400A range would be able to accommodate residmolecules that range in size from 25 to >200A in diameter. Thecumulative adsorption pore volume plot for Darco® carbon has pore volumein the 100-400A range as has Petrodarco A™ carbon (FIGS. 4 and 3) whilemost of the pore volume for the Co/Mo alumina catalyst is found below100A.

This can account for the high demetallation activity found forPetrodarco A™ and Darco® carbons. In fact, the demetallation activityfollows the same order as the amount of pore volume found in the200-400A range (FIGS. 1 and 3) and is: Petrodarco A™ >Darco® >Norit Rox™0.8>Alfa™ Carbon Activity

The amount of silica and alumina found in the activated carbon mayinfluence the cracking activity of the carbon. For instance, bothPetrodarco A™ and Darco® carbons contain >10% SiO₂ +Al₂ O₃ by weight andthese two carbon show higher 1000° F.+ conversion over an extended timeon stream (FIG. 5).

                  TABLE 15                                                        ______________________________________                                        CATALYST PROPERTIES                                                           Norit Rox ™ 0.8 (Peat Based Acidic Extruded)                               ______________________________________                                        Surface Area, m.sup.2 /g                                                                         862                                                        Real Density, g/cc  2.123                                                     Particle Density, g/cc                                                                            0.671                                                     Pore Volume, cc/g   1.019                                                     Average Pore diameter, A                                                                         47                                                         Alpha Value        5.5                                                        C, %               91.80                                                      H, %               0.54                                                       N, %               0.55                                                       S, %               0.78                                                       Ash, %             1.97                                                       Fe, (ppm)          202                                                        Al.sub.2 O.sub.3, (ppm)                                                                          737                                                        SiO.sub.2, %       1.63                                                       Cu (ppm)           <9                                                         K, %                0.0052                                                    Ni (ppm)           50                                                         V (ppm)            <9                                                         Na, (ppm)          197                                                        Ca, %               0.019                                                     Li, (ppm)          <47                                                        Mg, %               0.017                                                     ______________________________________                                    

                                      TABLE 16                                    __________________________________________________________________________    Hydroprocessing Results for Norit Rox ™ 0.8 (12-20 mesh)                   Sample                                                                        No. °F.                                                                       t(days)                                                                           Conversion                                                                          % deM                                                                             % deS                                                                             % deNi                                                                             % deV                                                                             % deCCR                                     __________________________________________________________________________    1   750                                                                              1.9 19.50 48.5                                                                              20.3                                                                              49.8 48.2                                                                              --                                          2   750                                                                              6.8 20.70 35.5                                                                              18.4                                                                              25.6 38.6                                                                              23.6                                        3   775                                                                              8.9 35.31 51.5                                                                              30.0                                                                              36.1 56.2                                                                              29.8                                        4   775                                                                              14.9                                                                              32.05 52.0                                                                              28.8                                                                              44.7 54.2                                                                              25.3                                        5   750                                                                              16.7                                                                              13.51 38.1                                                                              21.0                                                                              30.5 40.5                                                                              16.1                                        __________________________________________________________________________

EXAMPLE 7

A neat Darco® carbon catalyst was provided. The catalyst had theproperties shown in Table 9.

The feedstock was an atmospheric 650° F.+ resid having the propertiesshown in Table 17.

                  TABLE 17                                                        ______________________________________                                        650° F.+ Atmospheric Resid                                             ______________________________________                                        Carbon, %        84.76                                                        Hydrogen, %      12.29                                                        Nitrogen, %      0.78                                                         Oxygen, %        0.64                                                         Sulfur, %        0.55                                                         CCR              2.23                                                         Nickel, (ppm)    3.0                                                          Vanadium, (ppm)  0.96                                                         B.P. Range, °F.                                                                         Fraction                                                     420-650          16.9                                                         650-850          39.8                                                         850-1000         19.4                                                         1000° F.+ 23.9                                                         ______________________________________                                    

EXAMPLE 8

The feedstock of Table 17 was hydrotreated in a trickle bed micro unitreactor of standard design starting at 1500 psig H₂ partial pressure,5800 SCF H₂ /bbl circulation, and 0.5 hr-1 WHSV.

The trickle bed reactor was charged with 11.28 grams of DARCO® brandactivated carbon catalyst (12-20 mesh) and 30 cc of sand. The feeddelivery was 5.8 cc/hr. Standard presulfiding of the catalyst wasemployed with 2% H₂ S in hydrogen. All runs took place at 775° F. Therun time and pressure protocol was as follows:

(1) 1500 psig for 3 days

(2) 700 psig for 3 days

400 psig for 4 days

100 psig for 4 days

The micro unit reactor incorporated a bottoms receiver held at 200° C.to drive off volatiles; a 2° C. liquid cooled trap condensed low boilingcomponent. Gas samples were analyzed with a gas sampling system withbombs. Off gas volumes were measured with a wet test meter.

The results of the hydroprocessing are set forth below in Table 18. FIG.6 shows that 1500 psig hydrogen pressure produces the best demetallation(where about 98% demetallation is obtained). At 700 psig hydrogen, rapidaging occurs and demetallation decreases while below 700 psig hydrogen,not much metal is removed.

This example indicated that pressures >1000 psig are needed for goodlifetime of activated carbon catalysts.

                  TABLE 18                                                        ______________________________________                                        Hydroprocessing 650° F.+ Resid                                         at 775° F. and Different Pressures                                     Sample         Pressure                                                       No.    t(days) (psig)*   ppm(Ni + V)                                                                            % Demetallation                             ______________________________________                                        1      0.8     1000       .07     98                                          2      1.1     1000       .07     98                                          3      1.9     1000       .06     98                                          4      2.9     1000       .11     97                                          5      3.8     700        .42     90                                          6      5.1     700       1.04     74                                          7      6.8     700       1.92     48                                          8      7.9     400       3.34     16                                          9      10.0    400       3.90      2                                          10     10.8    400       4.80      0                                          11     13.8    100       3.59      9                                          ______________________________________                                         *At 2.9 days pressure changed from 1500 to 700 psig and at 6.8 days, 700      to 400 psig at 10.8 days, 400 to 100 psig.                               

EXAMPLE 9

Using a thermodynamics program, equilibrium calculations were made forcoke+water and coke+carbon dioxide reactions. Methane was used in thesecalculations for a model compound for coke. Table 19 shows than underhydroprocessing conditions of 750° F. and 500 to 1500 psig, water willreact with coke. Carbon dioxide also reacts with coke under theseconditions. Since hydroprocessing catalysts are designed to last atleast a year in a reactor, the use of water, oxygen, air, or carbondioxide would be sufficiently low that after a year, only about 10-20wt% of the carbon catalyst would be removed by oxidation. No greater than20% of the carbon catlayst should be oxidized in order to avoid collapseof the catalyst particle.

                  TABLE 19                                                        ______________________________________                                        Equilibrium Calculations                                                      (shows moles at equilibrium for components in equation)                       ______________________________________                                        Coke and Water Reaction                                                       2 CH.sub.4 + 3 H.sub.2 O ⃡ CO + CO.sub.2 + 3 H.sub.2              with 100 mol CH.sub.4 and l mole H.sub.2 O                                    1000 psig, 700° K.                                                     99.75         0.552    .039     .020  0.934                                   500 psig, 700° K.                                                      99.69         0.458    .0668   0.237  1.151                                   1500 psig, 700° K.                                                     99.789        0.606    .02756  0.1832 0.816                                   Coke and CO.sub.2 Reaction                                                    CH.sub.4 + CO.sub.2 ⃡ CO + H.sub.2 O + H.sub.2                    with 100 moles methane and 1 mole CO.sub.2                                    1000 psig, 700° K.                                                     99.86         0.80    0.332     .0584 0.216                                   500 psig, 700° F.                                                      99.81         0.75    0.435    0.0607 0.314                                   ______________________________________                                    

What is claimed is:
 1. A process for hydrotreating a hydrocarbon oilfeedstock, said process comprising hydrotreating said feedstock at atemperature of from about 500° F. to about 1200° F., a pressure of fromabout 0 psig to about 4000 psig, and a space velocity of from about 0.1to about 10 hr⁻¹ WHSV in the presence of a carbon-reactive oxidant and acatalyst composition comprising activated carbon possessing a porevolume in the 100 A to 400 A pore diameter range of at least about 0.08cc/g and an average pore diameter of from about 15 A to about 100 A,wherein said oxidant reacts with the activated carbon to form at least1% additional carbon surface area during said hydrotreating.
 2. Theprocess of claim 1 wherein said oxidant is selected from the groupconsisting of H₂ O, CO₂, and O₂.
 3. The process of claim 2 wherein saidoxidant comprises steam.
 4. The process of claim 3 wherein asteam-carbon reaction promoter is added.
 5. The process of claim 4wherein said steam-carbon reaction promoter is selected from the groupconsisting of KOH and K--Ca--O_(x).
 6. The process of claim 4 whereinsaid steam-carbon reaction promoter is selected from the groupconsisting of Fe, Ca, Ni, V, Ba, Mg, Mn, Zn, and P compounds.
 7. Theprocess of claim 1 wherein said catalyst composition further comprisesa) a molybdenum or tungsten component, and b) a cobalt or nickelcomponent, and said activated carbon possesses a pore volume in the 100A to 400 A pore diameter range of at least about 0.2 cc/g.
 8. Theprocess of claim 1 wherein said activated carbon possesses an averagepore diameter of from about 40 A to about 90 A.
 9. The process of claim1 wherein said activated carbon possesses a pore area in the 100 A to400 A pore diameter range of at least about 18 square meters per gram.10. The process of claim 1 wherein said activated carbon possesses apore area in the 100 A to 400 A pore diameter range of at least about 50square meters per gram.
 11. The process of claim 1 wherein saidactivated carbon possesses an Alpha value of from about 3 to about 6.12. The process of claim 1 in which the hydrocarbon oil feedstock ischaracterized by a distillation boiling point range such that thefraction boiling at over 650° F. comprises at least 70% of thehydrocarbon oil.
 13. The process of claim 1 wherein said process iscarried out in a fixed bed type reactor.
 14. The process of claim 1wherein said hydrotreating conditions include a temperature of fromabout 500° F. to about 1200° F., a pressure of from about 0 psig toabout 4000 psig, a space velocity of from about 0.1 to about 10 hr-1WHSV, and a steam partial pressure of at least 50 psig.
 15. The processof claim 1 wherein said hydrotreating conditions include a temperatureof from about 600° F. to about 1000° F., a pressure of from about 500psig to about 2500 psig, a space velocity of from about 0.2 to about 5hr-1 WHSV, and a steam partial pressure ranging from about 100 psig toabout 1000 psig.
 16. The process of claim 1 wherein said hydrotreatingconditions include a temperature of from about 700° to about 900° F., apressure of from about 1000 psig to about 2000 psig, a space velocity offrom about 0.3 to about 1.0 hr-1 WHSV, and a steam partial pressure offrom about 100 psig to about 500 psig.
 17. The process of claim 1wherein said hydrotreating conditions include a temperature of fromabout 500° F. to about 1200° F., a pressure of from about 0 psig toabout 4000 psig, a space velocity of from about 0.1 to about 10 hr-1WHSV, and an O₂ partial pressure of at least 50 psig where hydrogen isflushed from the reactor before O₂ is added.
 18. The process of claim 1wherein said hydrotreating conditions include a temperature of fromabout 500° F. to about 1200° F., a pressure of from about 0 psig toabout 4000 psig, a space velocity of from about 0.1 to about 10 hr-1WHSV, and a CO₂ partial pressure of at least 50 psig.
 19. The process ofclaim 1 wherein said hydrotreating includes demetallation,desulfurization, reduction of pentane insoluble asphaltenes, and thereduction of carbon residue of the feedstock.
 20. The process of claim19 wherein said demetallation is characterized by at least a 50%reduction in the combined content of nickel and vanadium compoundspresent in the feedstock.
 21. The process of claim 1 wherein thehydrotreating conditions include a hydrogen circulation rate of fromabout 300 SCF H₂ /bbl to about 6000 SCF H₂ /bbl of feedstock.